Liquid level control for well pumping apparatus



Oct. 3l, 1939. N. scoTT 2,177,950

LIQUID LEV-L CONTROL FOR WELL PUMPING APPARATUS Filed July 24, 1957 i i i i i ATTORNEY Patented Oct. 31, 1939 PATENT OFFICE LIQUID LEVELCONTROL FOR WELL PUlVIP- ING APPARATUS Clarence N. Scott, Houston, ".liex.; Bertha Britton Scott, administratrix of estate of said Clarence N. Scott, deceased Application July 24, 1937, Serial No. 155,359

11 Claims.

My invention relates to Well pumping apparatus for raising the iiuid in bored wells from the pumping depth in the well to the surface of the ground. ta.- It has particular but not exclusive relation to that class of such apparatus known as suckerrod pumps or working-barrels.

The uid entering such bored wells from the producing formation contains more or less gase- ,ufous fluid and the aim is to as far as possible sepa'- ratevin the well this gaseous content from the liquid and prevent its getting into the pump along with the liquid.

The liquid to be raised is conveyed tothe pump ,-cylinder or barrel by an intake pipe (usually called perforated pipe) attached to the bottom of same and submerged in the liquid in the well bore.' It is so arranged that gas released from the fluid on entering the Well bore is permitted annular passage formed between the suiction pipe, working barrel and discharge tubing perimeters and the inside surface of the well casing.

When properly constructed, these pumps can draw in and will discharge on each cycle fluid of high gas content and will not become gasbound or .gas-locked until the gas content of the intake fluid per stroke closely approaches 100% of the intake stroke displacement of the piston 30 7or plunger.

When selecting the size and speed of pump or working barrel to be installed, the aim is to have its plunger or piston displacement excessively large to insure getting the full production of oil 3.5,. that the Well is capable of drawing from the producing formation.

In practical operation this works out about as follows: On each cycle of the rpump plunger or piston (one up and one down stroke) more liquid 40iis pumped from the well than comes into it from the producing formation during that period of time and consequently the level of the liquid 'in the Well bore is lowered a little by each succeed-4 ing cycle until the uppermost perforation in the Aifxintake pipe (perforated pipe) or the open lo-wer endof the unperforated intake pipe is uncovered by the lowered liquid level in the well. The area soy uncovered and thus exposed to gas or air intake, while actually small, is nevertheless sufii- .v cient to instantly admit enough gas or air to the intake pipe and pump working chamber to drop the liquid from same (lose its suction) and the working chamber fills with gas or air and thus becomes gas-locked and the pump Y idles and 55;,gwill not draw in any more gas or air or any more to escape to the surface of the ground through the liquid nor discharge any until the liquid level in the well has built up in elevation very considerably. This is repeated continuously and my invention has as an object to prevent such operation.

I'he more excess pumping capacity, over and abovey that actually required to pump the potential production, that is provided the oftener suction is uncovered to gas or air and the higher the average bottom-hole pressure will be and the less will be the oil production of the well.

Production of fluid of an oil well, other things being equal, varies between maximum production when bottom-hole pressure is entirely removed and zerc'production when bottom-hole pressure is entirely removed and zero production when bottom-hole pressure is at its maximum and equals stabilized formation pressure.

`It will be seen that bottom-hole pressure instead of being maintained continuously at the minimum with 'the corresponding maximum production of liquid, is in reality, with pumping ap paratus as at present in the use and as operated, an average between the minimum bottom-hole pressure just before the liquid level uncovers the intake perforation and a very considerable builtup maximum bottom-holer pressure at the end of the gas-locked idling period.

Had it been practicable to slow the pump. down just before the liquid level uncovered the perforation or open end of the intake pipe so that itsspeedand capacity thereafter corresponded identically with the potential liquid production of the Well atI that liquid level and bottom-hole pressure, the pump would not have lost its suction and become gas-locked but would have continued full liquid displacement and discharge and bottom-hole pressure would have been maintained continuously at that low liquid level elevation and maximum production of oil would have been realized.

'Ihe same result would have been secured if, instead of slowing the speed of the pumpdown as proposed 'in the preceding paragraph, its liquid-discharging capacity had been reduced in some other manner to conform to the potential liquid production of the well and prevent the pumpfrom losing its suction and becoming gaslocked.y

It will be apparent that any regulation or control of the liquid discharging capacity of the pump, to adjust said capacity to the rate of production of liquid from the producing formation into the well bore at any predetermined minimum. liquid level elevation or bottom-hole presing from uncovering the pump suction to instantu-` l ly admit gas or air in such quantity as to cause-"'- the pump to lose its suction and become -gaslocked with its resulting idling and the consequent excessive building-up of liquid level in the well with the corresponding material increase in bottom-hole pressure.

Another object is to provide regulating and controlling means which will automatically main-5.

tain liquid level in the well bore or casing at a predetermined elevation with comparatively small variation in said elevation and thusprevent it from building up or increasing in elevation with the resulting increase in bottom-hole VI-general use in standard perforated pipes.

pressure and consequent reduction in the production of liquid flowing from the producing formation into the well.

Another object is to provide a method of operating bored wells which will maintain the maximum oil production by automatically maintain- 'ling the minimum bottom-hole pressure in same.

In the drawing herewith: ,f Fig. 1 is a central longitudinal section through the lower portion of a well installation embodying one form of my invention in which I use a fine :or narrow vertical regulating slot preferably in plural sections with supporting bridges.

Fig. 2 is a similar section but shows an alteri native construction in which I use a cleaning device to keep the narrow regulating slot open and -free from obstructions.

Fig. 3 is a similar section and shows another construction in which I use small frusto-conical regulating perforations disposed in vertical spacing, instead of the slot shown in Figs. 1 and 2.

Fig. 4 is another similar section and shows an- /other construction in which I use frusto-conical regulating perforations as in Fig. 3, but they are larger and are equipped with a cleaning device which keeps them open and free from obstructions and 'at the same time reduces the gas or airpassing area to the required small net.

Like parts shown in the several iigures have the same reference numbers.

I is the fragmentary lower end of the sucker- -frod pump or working barrel as is at present in general use. 2 is the standing valve (suction) assembly in the said pump. 3 is the suction or intake pipe of the pump. I have shown'it with the regular large perforations 4v as at present in One of these perforations is suiciently large to admit enough gas or air to the pump to equal full plunger displacement and cause it to become gasllocked, when said perforation is uncovered by liquid level in the well.

5 is a portion of the suction or intake pipe of the pump which has incorporated with it my regulating or controlling device. It connects `with the lower end of the pump or working barrel and is coupled to the suction or perforated pipe 3 by coupling 6. Or, suction pipe 3 may be omitted and liquid may enter through the open lower end of coupling G. Or, the coupling 6 may be substituted by a strainer l. as shown in Fig. 4. Or,v

the suction pipe 3 and the portion 5 may be combined and coupling 6 omitted as shown in Fig. 3.

8 is a regulating or controlling slot in the intake pipe. It increases in width from the perimeter of the pipe to the inside surface of same to prevent lodgment of obstructions. Its width at the perimeter of the pipe is narrow and its gas or air passing varea'is small so that even if uncovered by liquid level its entire length it will not pass enough gas or air to cause the pump to become gas-locked. As shown in Fig. 3, small perbe formed onor attached to bar II which isV hinged on links I2 on pins I3. I4 is a liquidimpact-propelling plate on bar II. Itobstructs the flow of liquid in the pipe 5 suiciently to cause bar II and Scrapers I0Ato .move up as the pump draws in fluid. Their weight is suflicient to cause them to fall to bottom position again as the liquid flow in the pipe intermittently ceases. Any other suitable formof cleaning device may be used. I may also provide means to clear openings I5 in Fig. 4.

In this embodiment, I5 are regulating or controlling perforations similar to but larger than 9. They are equipped with perforation cleaningpins I6, hinged on a supporting bar I'I. These pins, in addition to keeping the perforations I5 clear of obstructions, reduce the net gas or airpassing area of same to that required so that shouldliquid level uncover even all of them, the pump will not become gas-locked. The liquid as it flows upward in the intake pipe 5 causes these pins to move around in the perforations I5 and thus keep the iine annular openings around the pins open and free from obstructions. I8 is the inside surface of the well bore, casing, or liner.

Theoperation of the regulating or controlling device is as follows:

The well pump is discharging, by reason of its excessA capacity, more liquid than is flowing into the well from the producing formation and accordingly liquid level in the well is progressively lowered in elevation until the upper end of slot 8 or the uppermost perforation 9 or I5 is uncovered by the liquid level and gas or air in small quantity is admitted to the intake pipe 5 and pump I and reduces the liquid-discharging capacity of the said pump by the small amount that gas or air is initially admitted. If the liquid discharging capacity of the pump after its initial reduction is still in excess of the quantity' of liquid flowing into the well fromv the producing formation, the liquid level in the well will continue to lower and uncover more of the slot or another perforation thus admitting more gas or air to the pump and still further reducing its liquid-discharging capacity. .Just so long as the liquid-discharging capacity of the pump (which is the total displacement capacity of the piston or plunger less that portion of the displacement represented by gas or air), exceeds the quantity of liquid entering the well from the producing formation the liquid level in the well will continue to lower until the yliquid-discharging sure at the minimumwith maximum production of liquid.

In many of the installations in which my regulating device or method would be installed, plain regulating slots 8 or small perforations 9, Without any cleaning device, would be used. When conditions are such that ne slots and small perforations cause trouble by stopping up, cleaning devices can be used as contemplated.

I call attention of the fact, that the energy used in compressing the gas or air content of the pump is entirely recovered in this respect, that the gas or air compressed and discharged into the discharge tubing acts as an air lift and lightens the column of liquid in the same and accordingly reduces the oil pressure against which the pump must discharge.

What I claim is:

1. A well tubing, a deep well pump,-a fluid intake pipe at the lower end projectingr below the operating level of the liquid in the well, a regulating section thereonspaced above and below Athe operating liquidlevel, saidr regulating section having inlet openings therein spaced or disposed at different levels to allow a gradually increasing inlet or gas or air to saidv pump, and cleaning members `pivotally mounted to project loosely through said openings. to restrict said openings and to clear same of material tending to clog them.

`2. A deep well puinp, a well tubing, a uid intake `pipe at the lower end thereof, a gas or air regulating section of said tubing spaced upwardly from a lower liquid intake pipe, said' regulating Aco section having a vertically protracted opening of restricted lateral size, arms pivotally mounted on said pipe and projecting through said opening,

and means to move said arms to clear said openings, and means responsive to the movement of liquid in said pipe to agitate said arms.

4. A suction or intake pipe for deep well pumps, having liquid inlet openings in the lower portion thereof and gas or air regulating inlet openings in the 'upper portion thereof, said liquid openings being of ample size to prevent clogging, said gas or air openings being lrestricted horizontally but protracted vertically in number and dimension to' progressively and gradually increase restricted gas or air admission therethrough from the initial to the final uncovering thereof by the lowering liquid level in said well, said final uncovering being always less than that required to admit the full pump displacement of gas or air.

5. A suction or'intake pipe for deep well pumps, having liquid inlet openings in the lower portion thereof and gas or air regulating inlet openings inthe upper portion thereof, said liquid openings being of ample size to prevent clogging, said gas or air openings being restricted horizontally but protractedvertically in numberand dimension to progressively and gradually increase restrictedgas orlairy admission therethrough from the initial to the dinaliuncoveringthereof by the lowering liquidlevel insaid well `and means to clear said restrictedfopenings of; material tending to clog the same.n.--` -l ,6. Asuction orlintake pipefor. deep well pumps,

having liquidinlet openings inthe lower portionL thereof below the desired operating-liquid level in the well and gas or air regulating inlet openings in the upper portion thereof above and below the desired stabilized operating liquid level, said liquid openings being of ample size to prevent clogging, said gas or air openingsbeing restricted horizontally but protracted vertically in number and dimension to progressivelyand gradually increase restricted gas or air admission and correspondingly decrease liquid admission to said pipe and pump from initial uncovering of said gas or air openingsby the lowering liquid level until operating liquid level is stabilized by reduced liquid pumping capacity of the well pump by gas or air admissionto equal the liquid entering the well from the producing formation.

'7. A deep well reciprocating pump installation including a tubing, a standing Valve therein, a perforate intake pipe at the lower end of said tubing, a regulating section in said tubing above said intake vpipe and below said standing valve, said regulating section being imperforate except for a row of fine and narrowly restricted openings therein arranged in vertical direction so that lwhen said openings are progressively exposed as regulating section having a horizontally restricted but vertically protracted inlet for a limited amount y ,of gaseousvfluid, which is progressively increased in quantity as the liquid level in the well is lowered to expose a greater portion of said restricted inlet opening until liquid level is stabilized.

9. In a deep well reciprocating pump, a pump tubing, a standing valve thereon, a perforated intake pipe for liquid, an upper intake section for gas or air below said standing valve, said liquid intake pipe having unrestricted inlet for said liquid, said gas or air intake regulating section bel ing at a higher level and adapted to be exposed as the liquid level is lowered, said section having a narrow, restricted inlet for a limited amount of gas or air increasing in quantity by small graduations as the liquid level in the well is lowered by said pump, and until the liquid level is stabilized to permit the pumping of both gas and liquid corresponding with the rate of production of the well.

10. In a deep well reciprocating pump, a pump tubing, a. standing valve thereon, a perforate liquid intake pipe spaced below standing valve, a gas and air intake regulating section `between said valve and said liquid intake pipe, saidv regulating section having an opening therein for gas and air to allow a limited inlet thereto through which the inlet of gaseous fluid gradually increases as the liquid level is lowered and until it is stabilized and cleaning means loosely mounted to project through said opening'and to prevent clogging of the same. 5 e 11. In a deep Well pump installation, the combination of an intake pipe extending' below said pump, liquid inlet openings in the lower portion thereof, the upper regulating portion thereof be'- ing imperforate except for horizontally restricted openings progressively arrangedin a vertical direction so as to admit to said intake lpipe a restricted `quantity of gas or air gradually increasing as the liquid level in the well is lowered until the vlolume of liquid flowing from the producing formation into the Well and the volume of liquid delivered by the well pump are equalized and said 5 liquid level elevation is stabilized, and means to clear said restricted openings of material tending to clogthe same.

' CLARENCE N. SCOTT. 

